From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1754091Ab0CCAgh (ORCPT ); Tue, 2 Mar 2010 19:36:37 -0500 Received: from mx1.redhat.com ([209.132.183.28]:58095 "EHLO mx1.redhat.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1750830Ab0CCAgf (ORCPT ); Tue, 2 Mar 2010 19:36:35 -0500 Message-ID: <4B8DAEEA.8040306@redhat.com> Date: Tue, 02 Mar 2010 19:35:54 -0500 From: Masami Hiramatsu User-Agent: Mozilla/5.0 (X11; U; Linux i686; en-US; rv:1.9.1.7) Gecko/20100120 Fedora/3.0.1-1.fc11 Thunderbird/3.0.1 MIME-Version: 1.0 To: Mathieu Desnoyers CC: Ingo Molnar , Frederic Weisbecker , Ananth N Mavinakayanahalli , lkml , systemtap , DLE , Jim Keniston , Srikar Dronamraju , Christoph Hellwig , Steven Rostedt , "H. Peter Anvin" , Anders Kaseorg , Tim Abbott , Andi Kleen , Jason Baron Subject: Re: [PATCH -tip v3&10 02/18] kprobes: Introduce generic insn_slot framework References: <20100225133342.6725.26971.stgit@localhost6.localdomain6> <20100225133358.6725.82430.stgit@localhost6.localdomain6> <20100225152130.GB12635@Krystal> <4B8C7E23.1000302@redhat.com> <4B8DAAF2.203@redhat.com> <20100303003207.GA7176@Krystal> In-Reply-To: <20100303003207.GA7176@Krystal> X-Enigmail-Version: 1.0.1 Content-Type: text/plain; charset=ISO-8859-1 Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Mathieu Desnoyers wrote: > * Masami Hiramatsu (mhiramat@redhat.com) wrote: >> Masami Hiramatsu wrote: >>> Mathieu Desnoyers wrote: >>>> * Masami Hiramatsu (mhiramat@redhat.com) wrote: >>>>> Make insn_slot framework support various size slots. >>>>> Current insn_slot just supports one-size instruction buffer slot. However, >>>>> kprobes jump optimization needs larger size buffers. >>>> >>>> OK, so you end up having one insn slot cache for kprobes and one insn >>>> slot (eventually) for the static jump patching (which needs larger >>>> instruction slots than kprobes). That seems like a good way to ensure >>>> you do not use more memory than necessary. >>>> >>>> We could possibly go even further and automatically use the right insn >>>> slot cache given the size of the instruction entry that must be added (a >>>> bit like the memory allocator which have different pools for each >>>> allocation order). >>> >>> Sure, that will be simpler interface. >>> >>>> Possibly that using the terminology of "memory pools" rather than >>>> "cache" could be a better fit too. So what this really becomes is an >>>> instruction slot allocator and garbage collector. >>> >>> Ah, right. It would be better to rename kprobe_insn_pool() :) >> >> Hmm, I tried it. And finally, I found that this doesn't help >> to simplify code... Maybe it is better to postpone it until >> another user needs this feature. > > I guess it's a tradeoff between the genericity of the API you provide > and the complexity of the code that provides this API. So as you say, > maybe it's better to wait until more users appears before improving the > API. OK, I'll hold that generalizing patch until that. :) Thank you, -- Masami Hiramatsu e-mail: mhiramat@redhat.com